Staked rotor core for retaining magnets

ABSTRACT

Electric motors are disclosed. The motors are preferably for use in an automated vehicle, although any one or more of a variety of motor uses are suitable. The motors include lift, turntable, and locomotion motors.

CROSS-REFERENCE TO RELATED APPLICATIONS 1. Priority Applications

This is a divisional application of U.S. application Ser. No.15/047,265, filed Feb. 18, 2016, entitled STACKED ROTOR CORE FORRETAINING MAGNETS which claims priority from U.S. Provisional PatentApplication No. 62/117,810, filed Feb. 18, 2015, and entitled LOCOMOTIONGEARMOTOR FOR AUTOMATED GUIDED VEHICLE; U.S. Provisional PatentApplication No. 62/153,985, filed Apr. 28, 2015, and entitled INTEGRATEDMOTOR AND CONTROL FOR AUTOMATED GUIDED VEHICLE; and U.S. ProvisionalPatent Application No. 62/206,109, filed Aug. 17, 2015, and entitledGEARMOTOR FOR AUTOMATED GUIDED VEHICLE AND THE LIKE, the entiredisclosure of each of which is hereby incorporated by reference herein.

2. Contemporaneously Filed Applications

The present application is filed contemporaneously with U.S. patentapplication Ser. No. 15/047,244, entitled TRACTION MOTOR ASSEMBLY WITHGEAR-INTERCONNECTED WHEEL AND OUTPUT SHAFT, filed Feb. 18, 2016; U.S.patent application Ser. No. 15/047,249, entitled ELECTRIC MOTOR HAVINGLOW AXIAL PROFILE, filed Feb. 18, 2016; U.S. patent application Ser. No.15/047,256, entitled MOTOR HAVING RING FOR AXIALLY RETAINING STATOR,filed Feb. 18, 2016; and U.S. patent application Ser. No. 15/047,260,entitled MOTOR WITH ENCODER FLYWHEEL, filed Feb. 18, 2016. The entiredisclosure of each of the aforementioned contemporaneously filedapplications is hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to an electric motor assembly.The motor assembly is preferably for use in an automated vehicle or,more particularly, in a robot for use in a warehousing system. However,any one or more of a variety of motor assembly uses are suitable.

2. Discussion of the Prior Art

Those of ordinary skill in the art will appreciate that electric motorassemblies are often used in a variety of applications, including butnot limited to vehicles, automated devices, home appliances such asdishwashers and washing machines, exercise equipment, pumps, and more.

SUMMARY

According to one aspect of the present invention, a rotor is providedfor use in a motor. The rotor is rotatable about an axis. The rotorcomprises a core and a plurality of arcuately spaced apart magnets. Thecore defines a plurality of arcuately spaced apart magnet-receivingslots. The magnets are at least in part received in corresponding onesof the slots. Each of the magnets presents first and second generallyarcuately spaced apart magnet sides. Each of the slots includes a pairof arcuately spaced apart end openings defined adjacent respective onesof the magnet sides. The core includes a pair of arcuately spaced apartbridges associated with each of the slots, with each of the bridgesbeing radially adjacent a corresponding one of the end openings. Atleast one bridge of each pair is at least partly deformed to form asecurement portion, with the securement portion extending into thecorresponding one of the end openings and engaging the respective magnetto secure the respective magnet in the slot.

According to another aspect of the present invention, a rotor isprovided for use in a motor. The rotor is rotatable about an axis. Therotor comprises a core and a plurality of arcuately spaced apartmagnets. The core defines a plurality of arcuately spaced apartmagnet-receiving slots. The magnets are at least in part received inrespective ones of the slots. The core presents axially spaced apart topand bottom faces so as to define a core axial height therebetween. Thecore includes a plurality of securement portions each of which extendsalong and projects radially into a corresponding one of the slots toengage the respective magnet and thereby secure the respective magnet inthe slot. Each of the securement portions presents a total axial extentthat is less than the core axial height.

According to another aspect of the present invention, a method offorming a rotor for use in a motor is provided. The method comprises thesteps of (a) forming a core to define a plurality of arcuately spacedapart magnet-receiving slots; (b) inserting a plurality of magnets intocorresponding ones of the slots; and (c) deforming the core along eachof the slots to define a securement portion that extends along andprojects radially into the corresponding slot to engage the respectivemagnet and thereby secure the respective magnet in the slot.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Preferred embodiments of the present invention are described in detailbelow with reference to the attached drawing figures, wherein:

FIG. 1 illustrates a robot, shelving, and goods, wherein the robot isoperable to transport the shelving and goods;

FIG. 2 illustrates the robot of FIG. 1, including locomotion, turntable,and lift motor assemblies provided in the robot in accordance with apreferred embodiment of the present invention;

FIG. 3 is a perspective view of one of the locomotion motor assembliesand wheels of FIG. 2;

FIG. 4 is a cross-sectional view of the locomotion motor assembly andwheel of FIG. 3;

FIG. 4a is an enlarged, cross-sectional view of a portion of thelabyrinth formed between the wheel and the end block of the locomotionmotor assembly and wheel of FIG. 4;

FIG. 5 is an exploded perspective view of the locomotion motor assemblyand wheel of FIGS. 3 and 4;

FIG. 6 is an exploded perspective view of the locomotion motor assemblyand wheel generally opposite of that shown in FIG. 5;

FIG. 7 is a partially sectioned perspective view of the turntable motorassembly of FIG. 2;

FIG. 8 is a partially sectioned alternative perspective view of theturntable motor assembly of FIG. 7;

FIG. 9 is a cross-sectional view of the turntable motor assembly ofFIGS. 7 and 8;

FIG. 10 is an exploded perspective view of the turntable motor assemblyof FIGS. 7-9;

FIG. 11 is an exploded perspective view of the turntable motor assemblygenerally opposite of that shown in FIG. 10;

FIG. 12 is a top perspective view of a turntable motor assemblyaccording to a second preferred embodiment of the present invention;

FIG. 13 is a bottom perspective view of the turntable motor assembly ofFIG. 12;

FIG. 14 is an exploded top perspective view of the turntable motorassembly of FIGS. 12 and 13;

FIG. 15 is an exploded bottom perspective view of the turntable motorassembly of FIGS. 12-14;

FIG. 16 is a perspective view of the rotor of the turntable motorassembly of FIGS. 12-15, particularly illustrating the securementportions of the rotor core;

FIG. 17 is a top view of the rotor of FIG. 16;

FIG. 17a is an enlarged, sectioned top view of the rotor of FIGS. 16 and17, particularly illustrating the securement portions, ears, andstressed regions;

FIG. 17b is an enlarged, partially sectioned perspective view of therotor of FIGS. 16-17 a, taken along line 17 b-17 b of FIG. 17 a;

FIG. 17c is an enlarged, partially sectioned perspective view of therotor of FIGS. 16-17 b, taken along line 17 c-17 c of FIG. 17 a;

FIG. 18 is top perspective view of the stator retention ring of theturntable motor assembly of FIGS. 12-15;

FIG. 19 is a bottom perspective view of the stator retention ring ofFIG. 18;

FIG. 20 is a bottom view of the stator retention ring of FIGS. 18 and19;

FIG. 21 is a cross-sectional side view of the stator retention ring ofFIGS. 18-20;

FIG. 22 is a partially sectioned perspective view of the turntable motorassembly of FIGS. 12-15, particularly illustrating the disposition andfunction of the stator retention ring of FIGS. 18-21 and the portalextending between the motor chamber and the controller chamber;

FIG. 23 is an alternative partially sectioned perspective view of theturntable motor assembly of FIGS. 12-15 and 22, further illustrating thedisposition and function of the stator retention ring of FIGS. 18-21;

FIG. 24 is a bottom perspective view of the turntable motor assembly ofFIGS. 12-15, 22, and 23, with the lower end plate removed, furtherillustrating the disposition and function of the stator retention ringof FIGS. 18-21 and the portal of FIG. 22;

FIG. 25 is an enlarged side view, taken from the controller chambertoward the motor chamber, of the portal of FIGS. 22 and 24, particularlyillustrating the overlap of the stator retention ring lip over portionsof the portal edge;

FIG. 25a is an exploded view of FIG. 25, providing broader context tothe engagement between the stator ring lip and the portal edge;

FIG. 26 is an is an enlarged perspective view, taken from the motorchamber toward the controller chamber, of the portal of FIGS. 22 and24-25 a, particularly illustrating the overlap of the stator retentionring lip over portions of the portal edge;

FIG. 26a is an exploded view of FIG. 26, providing broader context tothe engagement between the stator ring lip and the portal edge;

FIG. 27 is a bottom view of the turntable motor assembly of FIGS. 12-15,and 22-24, with the lower end plate removed, further illustrating thedisposition and function of the stator retention ring of FIGS. 18-21,especially with regard to wire routing;

FIG. 28 is a cross-sectional side view, taken along line 28-28 of FIG.27, further illustrating the disposition and function of the statorretention ring of FIGS. 18-21;

FIG. 29 is a cross-sectional side view, taken along line 29-29 of FIG.27, further illustrating the disposition and function of the statorretention ring of FIGS. 18-21, especially with regard to fastenerinsulation;

FIG. 30 is an enlarged, partially sectioned bottom perspective view ofthe turntable motor assembly of FIGS. 12-15, 22-24, and 27-29, furtherillustrating the disposition and function of the stator retention ringof FIGS. 18-21, especially with regard to redundant stator coreinsulation in cooperation with the end caps;

FIG. 31 is a partially sectioned top perspective view of a portion ofthe of the turntable motor assembly of FIGS. 12-15, particularlyillustrating the encoder flywheel assembly and associated encoderhousing;

FIG. 32 is a top perspective view of the encoder flywheel assembly andencoder housing of FIG. 31, with the base plate removed;

FIG. 33 is a bottom perspective view of the encoder flywheel assemblyand encoder housing of FIGS. 31 and 32;

FIG. 34 is a cross-sectional side view of the encoder flywheel assemblyand encoder housing of FIGS. 31-33;

FIG. 35 is a side view of the encoder flywheel assembly and rotor of theturntable motor assembly of FIGS. 12-15, with the base plate removed andthe end plate shown schematically;

FIG. 36 is an exploded bottom perspective view of the encoder flywheelassembly and encoder housing of FIGS. 31-35, with the base plateremoved; and

FIG. 37 is an exploded top perspective view of the encoder flywheelassembly and encoder having of FIGS. 31-36, with the base plate removed.

The drawing figures do not limit the present invention to the specificembodiments disclosed and described herein. The drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the preferred embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is susceptible of embodiment in many differentforms. While the drawings illustrate, and the specification describes,certain preferred embodiments of the invention, it is to be understoodthat such disclosure is by way of example only. There is no intent tolimit the principles of the present invention to the particulardisclosed embodiments.

Furthermore, unless specified or made clear, the directional referencesmade herein with regard to the present invention and/or associatedcomponents (e.g., top, bottom, upper, lower, inner, outer etc.) are usedsolely for the sake of convenience and should be understood only inrelation to each other. For instance, a component might in practice beoriented such that faces referred to as “top” and “bottom” are sideways,angled, inverted, etc. relative to the chosen frame of reference.

In a preferred embodiment of the present invention, a robot 10 isprovided. The robot 10 preferably includes a main body 12 supported on achassis (not shown), a support platform 14, and a pair of rotatable,ground-engaging wheels 16 enabling the robot 10 to have a zero-turnradius.

The robot 10 is preferably configured to transport goods in a warehouseenvironment. For instance, in a preferred embodiment, the robot 10 isconfigured to transport shelving 18 and various goods 20 supportedthereon through a warehouse environment. More particularly, the robot 10is preferably operable at least to (1) lift the shelving 18 andassociated goods 20 on the platform 14; (2) rotate at least a portion ofthe platform 14 so as to appropriately orient the shelving 18 and goods20 supported by the platform 14; (3) transport the shelving 18 and goods20 on the platform 14 from one location to another in the warehouse,making use of the wheels 16; (4) deposit the shelving 18 and goods 20 attheir new location through lowering of the platform 14; and (5)completely disengage from the shelving 18 and goods 20 via lowering ofthe platform 14 so as to no longer be in contact with the shelving 18and/or goods 20.

The robot 10 is preferably provided with numerous features to enablesuch operation, including but not limited to one or more printed circuitboards, sensors, cameras, and communication devices. A control system(not shown) is also preferably provided to control each robot 10 and tosynchronize operation of multiple robots 10 in a warehouse.

The robot 10 is preferably battery-powered and rechargeable.

In a preferred embodiment, the robot 10 includes four (4) motorassemblies: a pair of locomotion or traction motor assemblies 110, eachof which is associated with a respective one of the wheels 16 to form arespective traction assembly 112, and which cooperatively enable therobot 10 to travel through the warehouse; a turntable motor assembly 310operable to rotate and stabilize at least a portion of the platform 14;and a lift motor assembly 710 operable to raise the platform 14,preferably but not necessarily with the assistance of a scissor liftmechanism or other lifting aid.

Preferably, the locomotion motor assemblies 110 and the lift motorassembly 710 are mounted directly to the chassis (not shown). Theturntable motor assembly 310 is preferably mounted to the platform 14.

Although the locomotion motor assemblies 110, the turntable motorassembly 310, and the lift motor assembly 710 are preferably part of therobot 10 and function generally as described above, it is noted that itis within the scope of the present invention for the motor assemblies toinstead be provided in an alternative application and/or to be providedseparately from one another. For instance, the locomotion motorassemblies might instead be provided for use in an electric vehicle forhuman transport, the turntable motor assembly might be used to operate arotating display, or the lift motor assembly might be used to raise andlower a load that is in no manner associated with a warehouse operation.Furthermore, certain features of each of the motor assemblies may beused in entirely different applications than shown. For example, certainaspects of the locomotion motor assembly 110 might be capable of use inmotor assemblies that are not used to drive or propel a wheeled vehicle,including but not limited to motor assemblies similar to the turntablemotor assembly 310 or the lift motor assembly 710.

Locomotion Motor Assembly

With initial reference to FIGS. 3-6, the traction assembly 112 inaccordance with a first preferred embodiment of the present invention isillustrated. As noted previously, the traction assembly 112 preferablyincludes one of the locomotion or traction motor assemblies 10 and oneof the wheels 16.

The locomotion motor assembly 110 preferably includes a motor 114including a rotor 116 rotatable about a rotor axis. The motor 114further preferably includes a stator 118.

The locomotion motor assembly 110 further preferably includes an outputshaft 120, a motor case 122, a controller 124, and a controller case126.

The locomotion motor assembly 110 is preferably oriented such that therotor axis is a horizontal axis. The rotor 116 and the stator 118 arepreferably positioned at an axially inner end (relative to the robot 10in a broad sense) of the traction assembly 112, while the wheel 16 ispositioned at an axially outer end (relative to the robot 10 in a broadsense) of the assembly 112. It is permissible according to some aspectsof the present invention, however, for the locomotion motor assembly tobe alternatively oriented.

Stator Overview

As best shown in FIGS. 4-6, the stator 118 preferably includes agenerally toroidal stator core 128 and wiring 130 wound about the statorcore 128 to form a plurality of coils 132. The stator core 128 ispreferably a laminated stator core comprising a plurality of stackedlaminations (not shown), although it is permissible for the stator coreto be non-laminated. The stator core 128 preferably comprises aferromagnetic material such as steel, although use of any one or moreelectrically conductive materials is permissible without departing fromthe scope of the present invention.

The laminations of the stator core 128 are preferably interlocked torestrict relative axial shifting, although other configurations (e.g.,non-interlocked laminations) are permissible.

The stator core 128 preferably defines an axis. Most preferably, theaxis is co-axial with the axis of the rotor 116, although offset orskewed axes are permissible according to some aspects of the presentinvention.

Preferably, the stator core 128 includes a plurality of arcuately spacedapart, generally radially extending teeth 134. More particularly, in apreferred embodiment, each of the teeth 134 includes a generallycircumferentially extending yoke 136, a generally radial arm 138extending from the yoke 136, and a crown 140 extending generallycircumferentially from the arm 138.

The motor 114 is preferably an inner rotor motor, with the stator 118 atleast substantially circumscribing the rotor 116. More particularly,each yoke 136 preferably engages a pair of adjacent yokes 136, such thatthe yokes 136 cooperatively present an outer circumferential stator coreface 142. The crowns 140 cooperatively present a discontinuous innercircumferential stator core face 144 that faces the rotor 116. Acircumferentially extending radial gap 146 is preferably formed betweenthe inner circumferential stator core face 144 and the rotor 116. Use ofan outer rotor motor is permissible according to some aspects of thepresent invention, however.

Furthermore, it is permissible according to some aspects of the presentinvention for the stator core to be alternatively configured. Amongother things, for instance, the stator core could comprise a pluralityof interconnected multi-tooth segments, comprise one or more helicallywound laminations, or comprise stacked annular laminations each formedfrom a single punched strip.

The stator core 128 is preferably electrically insulated by means of aplurality of discrete, electrically insulative end caps 148 securedrelative to the core 128. Each end cap 148 preferably provides both aphysical and electrical barrier between the coils 132 and the statorcore 128, with a pair of end caps 148 fitted over opposite axial sidesof a corresponding tooth 134 so as to in part encompass the tooth 134.

The end caps 148 preferably comprise a plastic or synthetic resinmaterial, although any one or more of a variety of materials havingelectrically insulative properties may be used.

Furthermore, it is noted that use of any one or more of a variety ofalternative or additional insulation means, including but not limited tothe use of electrically insulative overmolding, powder-coating, and/orliners, is permissible according to some aspects of the presentinvention. It is also permissible according to some aspects of thepresent invention for the stator core to be devoid of electricalinsulation.

The coils 132 are preferably wound about the arms 138 of the teeth 134.More particularly, a slot 150 is defined between each adjacent pair ofteeth 134. The coils 132 are preferably wound about the teeth 134 andthrough the slots 150 so as to circumscribe respective ones of the arms138.

The stator 118 preferably includes twelve (12) teeth 134 defining twelve(12) slots 150 therebetween, with twelve (12) coils 132 being woundabout the teeth 134. Alternate numbers of teeth, slots, and/or coils arepermissible according to some aspects of the present invention, however.

The wiring 130 forming the coils 132 is preferably electricallyconductive wiring wound multiple times about each tooth 134 to form aplurality of turns or loops. The wiring 130 is preferably formed ofcopper or aluminum, although any one or more of a variety of electricalconductive materials or a combination thereof may be used within theambit of the present invention.

Furthermore, the wiring 130 may be coated or uncoated.

As is customary, the wiring 130 is wound around the teeth 134 in aparticular manner according to the configuration and desired performancecharacteristics of the locomotion motor assembly 110.

Rotor Overview

As best shown in FIGS. 4-6, the rotor 116 preferably includes a rotorcore 152, a plurality of arcuately arranged magnets 154, and a rotorshaft 156 (or, alternatively, a motor shaft 156) that extends along andis rotatable about the rotor axis.

The rotor core 152 is preferably a laminated rotor core, although it ispermissible for the rotor core to be non-laminated. The laminations ofthe rotor core 152 are preferably interlocked, although otherconfigurations (e.g., non-interlocked laminations) are permissible.

The rotor core 152 preferably comprises a ferromagnetic material such assteel, although use of any one or more electrically conductive materialsis permissible without departing from the scope of the presentinvention.

The rotor core 152 is preferably generally decagonal in cross-section soas to define ten (10) magnet-mounting faces 158, although other shapes(e.g., round or hexagonal) are permissible according to some aspects ofthe present invention.

The magnets 154 are preferably mounted to corresponding ones of themagnet-mounting faces 158. In a preferred embodiment, ten (10) magnets154 are provided and define ten (10) poles. Magnet numbers may varywithin the ambit of the present invention, however.

In keeping with the above-described preferred stator core 128, whichdefines twelve (12) slots, it is noted that the motor 114 is preferablya twelve (12) slot, ten (10) pole motor. It is permissible according tosome aspects of the present invention, however, for the locomotion motorassembly to have a different number of slots and poles maintaining thepreferred six (6) slot:five (5) pole ratio or for an entirely differentslot to pole ratio to be defined.

The magnets 154 are preferably mounted to corresponding ones of themagnet-mounting faces 158 through use of a glue or adhesive. In apreferred embodiment, for instance the magnets 154 are retained on themagnet-mounting faces 158 through use of a two step acrylic, one-part,dual-cure, thixotropic magnet bonding adhesive with a solvent-lessactivator.

The adhesive is preferably applied to each magnet-mounting face 158 andto each magnet 154. The adhesive may applied in the form of a bead, in apattern (e.g., a grid or a plurality of evenly spaced apart dots), in arandom dispersion, or over the entire surface.

The rotor 116 is preferably additionally wrapped with a thin film (notshown) to provide redundant magnet 154 retention. Preferably, the filmis heat shrunk over the rotor 116. In addition to providing retention ofthe magnets 154 in whole, the thin film is also preferably operable toretain any chips that might break away from the magnets 154. (Thelikelihood of such chip formation is greater if a non-preferred magnetmaterial such as ferrite is used, rather than a preferred,unlikely-to-chip neodymium iron boron magnet material as identifiedbelow.)

The magnet retention means may vary from the preferred combinationdescribed above without departing from some aspects of the presentinvention, however. For instance, it is permissible according to someaspects of the present invention for the thin film to be omitted and/orfor the magnets to be retained using alternative or additionalmechanical means or an alternative or additional adhesive. Preferably,however, the magnet retention means are sufficient to restrict magnetdislodgement at all rotational speeds of the rotor 116. The magnetretention means should also be sufficient to restrict magnetdislodgement at all possible magnet temperatures during operation.

The magnets 154 are preferably rare earth magnets. More particularly,the magnets 154 are preferably thirty-five (35) uh, one hundred eightydegrees Celsius (180° C.) grade neodymium iron boron magnets. Othermagnet types may be used without departing from some aspects of thepresent invention, however. For instance, according to some aspects ofthe present invention, the magnets might be of a lower grade and/orcomprise ferrite.

In a preferred embodiment, the magnets 154 include nickel-copper-nickelplating. Alternative plating or no plating is permissible, however.

The magnets 154 preferably cooperatively present an outercircumferential rotor face 160.

The gap 146 is preferably formed between the inner circumferentialstator core face 144 and the outer circumferential rotor face 160.

Motor Case Overview

As noted previously, the motor assembly 110 preferably includes themotor case 122. As best shown in FIG. 4, the motor case 122 preferablydefines a motor chamber 162 that at least substantially receives themotor 114 (i.e., at least substantially receives the rotor 116 and thestator 118).

More particularly, in a preferred embodiment, the motor case 122includes a shell 164, an axially inner endshield 166, and an axiallyouter end block 168. The shell 164 preferably extends between andinterconnects the endshield 166 and the end block 168.

The shell 164 and the end block 168 are preferably integrally formed(e.g., from a single casting), although non-integral formation ispermissible.

Preferably, the shell 164 includes a generally cylindrical main body 170and a radially or laterally extending flange 172, although other shapes(e.g., a polygonal main body) are permissible according to some aspectsof the present invention. The flange 172 preferably abuts or merges withthe end block 168.

It is preferred that the shell 164 at least substantially circumscribesthe stator 118 and in part defines the motor chamber 162, such that themotor chamber 162 at least substantially receives the stator 118 and therotor 116.

In a preferred embodiment, the shell 164 comprises metal. Moreparticularly, in the preferred embodiment, the shell 164 comprises castaluminum.

The shell 164 is preferably fit on the stator core 128 via aninterference fit, although non-interference fits (e.g., tight fits orslip fits) fall within the scope of the present invention,

The endshield 166 preferably at least substantially encloses an innerend of the motor chamber 162. The end block 168 preferably at leastsubstantially encloses an outer end of the motor chamber 162.

Furthermore, the endshield 166 preferably supports the rotor 116. Moreparticularly, the motor assembly 110 preferably includes a rotor shaftbearing 174 that rotatably supports the rotor shaft 156 and, in turn,the rotor 116 in a broad sense. The endshield 166 preferably defines arotor shaft bearing hub 176 that at least in part receives the rotorshaft bearing 174.

Integral Ring Gear

As noted above, the rotor 116 preferably includes the rotor or motorshaft 156. Preferably, the rotor shaft 156 comprises the output shaft120, which includes an output gear 178. More particularly, the outputshaft 120 (or, alternatively, the rotor or motor shaft 156) preferablypresents an axially outer end 180 comprising the output gear 178, whichis preferably a pinion gear. Furthermore, the wheel 16 preferablypresents a wheel gear 182 that drivingly intermeshes with the outputgear or pinion gear 178, such that rotation of the output gear 178imparts rotation to the wheel 16.

More particularly, the wheel 16 preferably includes a hub 184, a rim 186circumscribing the hub 184, a tire 188 circumscribing the hub 184 andthe rim 186, and a wheel shaft 190 fixed relative to the hub 184 forrotational movement therewith.

The wheel 16 is preferably rotatable about a wheel axis, with the wheelshaft 190 preferably extending along the wheel axis. The wheel axis ispreferably laterally offset from and at least substantially parallel tothe rotor axis, such that the rotor shaft 156 and the wheel shaft 190are laterally offset and generally parallel, although alternativerelative dispositions are permissible according to some aspects of thepresent invention.

Furthermore, the rotor shaft 156 and the wheel shaft 190 preferablyextend at least in part alongside each other. Such axial overlap enablesa decrease in the axial envelope required for the wheel 16 and thepinion gear 178 in a broad sense. Advantageous effects of such adecrease will be discussed in greater detail below.

The assembly 112 preferably includes a pair of wheel bearings 192 and194 rotatably supporting the wheel shaft 190. More particularly, the endblock 168 of the motor case 122 preferably defines a wheel bearing hub184 that receives the pair of wheel bearings 192,194 such that the wheelbearings 192 and 194 support the wheel shaft 190 on the motor case 122.

Preferably, the wheel shaft 190 is integrally formed with the hub 184 ofthe wheel 16, although non-integral formation is permissible accordingto some aspects of the present invention.

In a preferred embodiment, the hub 184 presents the aforementioned wheelgear 182. More particularly, the wheel gear 182 is preferably integrallyformed with the hub 184 and comprises a ring gear 196 having a pluralityof arcuately spaced apart, radially inwardly directed ring gear teeth196 a defined about the hub 184 in spaced relation to the wheel shaft190. The pinion gear 178 of the output shaft 120, in contrast,preferably includes a plurality of arcuately spaced apart, generallyradially outwardly directed pinion gear teeth 178 a that engage theteeth 196 a of the ring gear 196 to drive rotation of the ring gear 196and, more broadly, the wheel 16 in its entirety.

It is particularly noted that provision of the ring gear 196 formedintegrally with the wheel hub 184 enables a decrease in the axialenvelope required for the ring gear 196 and the pinion gear 178 and,more broadly, the wheel 16 and the pinion gear 178. Advantageous effectsof such a decrease will be discussed in greater detail below.

The hub 184 (including the integrally formed ring gear 196) and theoutput shaft 120 preferably comprise powder-coated metal, although othermaterials may permissibly be used for some or all of theabove-referenced elements without departing from the scope of someaspects the present invention.

In a preferred embodiment, the pinion gear 178 and the ring gear 196define a single stage gear transmission 198 from the motor assembly 110to the wheel 16. That is, the motor assembly 110 itself is devoid ofgearing. It is permissible according to some aspects of the presentinvention, however, for a more complex transmission including additionalgears to be provided. For example, in an alternative multi-stageembodiment, the output shaft may be connected to the rotor shaft by two(2) or more intermeshing gears.

Gear Lubrication and Sealing

In a preferred embodiment, the motor case 122 and the hub 184cooperatively define a gear chamber 200 in which the pinion gear 178 andthe ring gear 196 intermesh. More particularly, the end block 168 andthe hub 184 preferably define the gear chamber 200. Thus, the end block168 preferably at least in part defines both the motor chamber 162 andthe gear chamber 200.

Furthermore, as best shown in FIG. 4, the motor chamber 162 and the gearchamber 200 are preferably in fluid communication.

Preferably, the hub 184 and the end block 168 cooperatively define adynamic seal interface 202 therebetween, with the seal interface 202being in communication with the gear chamber 200.

A seal 204 is preferably provided at the interface 202 to at leastsubstantially prevent the transfer of contaminants or other materialsthereacross. However, it is permissible according to some aspects of thepresent invention the seal to be omitted. More particularly, it is notedthat the interface 202 preferably comprises a labyrinth 206. Thelabyrinth 206 is configured to restrict leakage of oil or otherlubricants from the gear chamber 200 while also preventing ingress ofcontaminants into the gear chamber 200. Most preferably, the interface202 (i.e., the labyrinth 206) is filled with a lubricant that restrictsmigration of contaminants into the gear chamber 200. The labyrinth 206will be described in greater detail below.

It is noted that the preferred embodiment described above isparticularly suited for use of a heavier grease as a lubricant. Thegrease preferably is viscous enough to not drip throughout the motorchamber 162 and/or the gear chamber 200.

Preferably, the ring gear 196 circumscribes a gear chamber cavity 208,with the grease at least in part filling the gear chamber cavity 208 andbeing forced into the ring gear 196 by means of centrifugal force. Thegrease thereby lubricates the ring gear 196 and at least in partprevents the migration of dust and foreign debris or other contaminantsinto the gear chamber 200.

The grease further preferably at least in part fills the interface 202so as to lubricate the rotation of the hub 184 relative to the end block168 and at least in part prevents the migration of dust and foreigndebris or other contaminants into the gear chamber 200.

In a preferred embodiment and as best shown in FIG. 4a , the labyrinth206 includes a plurality of alternately radially and axially extending(i.e., orthogonally oriented relative to each other) sections 206 a, 206b (shown filled with the seal 204), 206 c, 206 d, and 206 e. More orfewer sections may be provided without departing from the scope of thepresent invention, however. Furthermore, relative orientations betweenthe sections may be non-orthogonal (e.g., acutely angled, etc.) or acombination of orthogonal and non-orthogonal.

More particularly, the end block 168 preferably includes acircumferential recess 210 that extends axially inwardly relative to thewheel 16. The hub 184 preferably includes a circumferential wall 212that extends axially inwardly into the recess 210. The recess 210 andthe wall 212, along with the rim 186, cooperatively at least in partdefine the labyrinth 206.

In still greater detail, it is preferred that the labyrinth sections 206a, 206 b, 206 c, 206 d, and 206 e are in part defined by correspondingend block surfaces 168 a, 168 b, 168 c, 168 d, and 168 e, and further inpart defined by a corresponding face 186 a presented by the rim 186 andcorresponding faces 212 b, 212 c, 212 d, and 212 e defined by thecircumferential wall 212.

Preferably, the labyrinth sections 206 a and 206 e both extend at leastsubstantially radially and are at least substantially axially aligned.Likewise, corresponding surfaces 168 a,168 e extend at leastsubstantially radially and are at least substantially axially aligned.Yet further, the faces 186 a,212 e extend at least substantiallyradially are at least substantially axially aligned.

Furthermore, the surfaces 168 b,168 c,168 d (which generally define therecess 210) are preferably at least in part in axial and radialalignment with the circumferential wall 212. If desired, according tosome aspects of the present invention, the labyrinth may bealternatively formed along only one side (radially inner or outer side)of the circumferential wall (e.g., one of the surfaces 168 b or 168 dmay be removed).

Furthermore, the seal 204 is preferably at least in part disposed in therecess 210 so as to at least substantially fill the labyrinth section206 b. However, according to some aspects of the present invention, theseal may be alternatively positioned radially inside the circumferentialwall.

Axially Disposed Controller

As noted previously, the motor assembly 110 preferably includes thecontroller 124 and the controller case 126. The controller case 126preferably defines a controller chamber 214 that at least substantiallyreceives the controller 124.

The controller 124 is preferably configured to at least in part controloperation of the motor 114.

Furthermore, in a preferred embodiment, the controller 124 is positionedaxially adjacent the motor 114. More particularly, as will be discussedin greater detail below, the output gear 178 or pinion gear 178 ispreferably positioned adjacent the outer end 180 of the output shaft120, while the controller 124 is positioned adjacent an axiallyopposite, inner end 216 of the output shaft 120.

The controller 124 preferably includes a printed circuit board 218 and aplurality of electronic components 220 (e.g., resistors, capacitors,inductors, transistors, processors, switches, etc.) mounted on theprinted circuit board 218. However, it is permissible for the controller124 to be configured in any manner known in the art.

In a preferred embodiment, the printed circuit board 218 presents ageometric center that lies on or at least near the rotor axis. However,offset positioning is permissible according to some aspect of thepresent invention.

In a preferred embodiment, as noted previously, the motor case 122includes the shell 164, the inner endshield 166, and the outer end block168. The shell 164 preferably extends between and interconnects theendshield 166 and the end block 168.

The controller case 126 preferably includes an inner base 222, an outercover 224, and a generally axially extending sidewall 226 extendingbetween and interconnecting the base 222 and the cover 224. The base 222preferably at least substantially encloses an inner end of thecontroller chamber 214, while the cover 224 preferably at leastsubstantially encloses an outer end of the controller chamber 214.

The base 222 and the sidewall 226 are preferably integrally formed,while the cover 224 is preferably a discrete component. Most preferably,the cover 224 is integral with the endshield 166 of the motor case 122.Alternative formation is permissible without departing from the scope ofsome aspects of the present invention, however.

The base 222 and the cover 224 are preferably generally circular. Thesidewall 226 is preferably generally cylindrical. Other base, cover, andsidewall shapes are permissible, however.

The controller 124 may be mounted in any suitable manner within thecontroller chamber 214. For instance, the controller 124 could befastened to mounting bosses (not shown in detail) projecting from thecover 224 of the controller case 126.

In a preferred embodiment, the controller chamber 214 and, in turn, thecontroller 124, is at least substantially encapsulated. Furthermore, oneor more gaskets (not shown) are preferably provided to restrict dust andwater ingress into the controller chamber 214.

Preferably, a wire opening 228 is defined in the endshield 166. Wires(not shown) connecting the controller 124 and the motor 114 arepreferably routed through the wire opening 228.

In a preferred embodiment and as best shown in FIG. 3, the controllercase 126 preferably includes a plurality of circumferentially spacedapart mounting tabs 230 each extending generally radially outwardly fromthe sidewall 226. Each mounting tab 230 preferably defines afastener-receiving opening 232. Similarly, the endshield 166 of themotor case 122 (or, alternatively, the cover 224 of the controller case126) preferably includes a plurality of circumferentially spaced apartmounting projections 234 each extending generally radially outwardly.Each mounting projection 234 preferably defines a fastener-receivingaperture 236 (see, for instance, FIG. 5). Correspondingfastener-receiving orifices 238 are also formed in the end block 168. Afastener 240 preferably extends through each corresponding set ofopenings/apertures/orifices 232,236,238 to secure the controller case126 to the motor case 122. It is noted however, that alternativeapproaches utilizing fasteners, latches, adhesives, welds, and/or otherdevices or techniques are permissible.

The controller case 126 and the motor case 122 are preferably at leastsubstantially axially aligned. More particularly, in a preferredembodiment, the shell 164 of the motor case 122 and the sidewall 226 ofthe controller case 126 are at least substantially aligned. Moreparticularly, the shell 164 and the sidewall 226 preferably have atleast substantially equivalent wall thicknesses and form at leastsubstantially coaxial cylinders having at least substantially equaldiameters (both inner and outer).

It is therefore also preferable that the controller chamber 214 and themotor chamber 162 present at least substantially equal diameters. Morebroadly, however, it is preferred that the controller chamber 214 andthe motor chamber 162 present at least substantially equal radial orlateral dimensions (e.g., as would be the case for chambers havinggenerally congruent oval or rectangular cross-sections).

It is particularly noted that provision of an integral outer ring gear196 enables a decrease in the axial envelope required for the ring gear196 and the pinion gear 178. Furthermore, the previously describedextension of the rotor shaft 156 and the wheel shaft at least in partalongside each other enables a decrease in the axial envelope requiredfor the wheel 16 and the pinion gear 178 in a broad sense. Suchreductions in required axial space at least in part enable the additionof the controller 124 and the associated controller case 126 axiallyadjacent the motor 114 without exceeding the allowable axial envelopefor the motor assembly 110 as a whole.

Turntable Motor Assembly—First Preferred Embodiment

FIGS. 7-11 illustrate the turntable motor assembly 310 as shown in FIG.2. It is initially noted that, with certain exceptions to be discussedin detail below, certain elements of the turntable motor assembly 310are the same as or very similar to those described in detail above inrelation to the locomotion motor assembly 110. Therefore, for the sakeof brevity and clarity, redundant descriptions and numbering will begenerally avoided here. Unless otherwise specified, the detaileddescriptions of certain of the elements presented above with respect tothe locomotion motor assembly 110 should therefore be understood toapply at least generally to the turntable motor assembly 310, as well.

Among other things, the turntable motor assembly 310 preferably includesa motor 312. The motor 312 preferably includes a stator 314 and a rotor316 rotatable about an axis.

The stator 314 preferably includes a generally toroidal stator core 318comprising a plurality of teeth 320 (shown schematically). The statorcore 318 is preferably a laminated stator core, although it ispermissible for the stator core to be non-laminated. The stator core 318preferably comprises a ferromagnetic material such as steel, althoughuse of any one or more other electrically conductive materials ispermissible without departing from the scope of the present invention.

The stator 314 further preferably includes a plurality of coils 322(shown schematically) wound about the stator core 318.

The rotor 316 preferably includes a rotor shaft 324 that is rotatableabout an axis, a rotor core 326 fixed to the rotor shaft 324 to rotatetherewith, and a plurality of circumferentially spaced magnets 328 fixedto the rotor core 326 to rotate therewith.

The rotor core 326 is preferably a laminated rotor core, although it ispermissible for the rotor core to be non-laminated. The rotor core 326preferably comprises a ferromagnetic material such as steel, althoughuse of any one or more electrically conductive materials is permissiblewithout departing from the scope of the present invention.

The motor 312 is preferably an inner rotor motor, with the stator 314 atleast substantially circumscribing the rotor 316.

The motor assembly 310 further preferably includes a motor housing 330defining a motor chamber 332. The motor 312 (i.e, the stator 314 and therotor 316) is preferably least substantially received in the motorchamber 332.

In a preferred embodiment, the motor housing 330 includes an upper endplate 334 and a shell 336. The upper end plate 334 is preferably fixedrelative to the shell 336.

The rotor shaft 324 preferably includes a connection end 338 and anencoder end 340 axially spaced from and opposite the connection end 338.The rotor shaft 324 further preferably includes a connection portion 342adjacent the connection end 338, a cantilevered portion 344 adjacent theencoder end 340, and a bearing-supported portion 346 extending betweenand interconnecting the connection portion 342 and the cantileveredportion 344.

The connection portion 342 preferably supports a connector 348configured for engagement with a device or structure such as a turntable(not shown) of an automated guided vehicle such as the robot 10 of FIGS.1 and 2.

Preferably, the motor assembly 310 includes a shield 350 for protectingthe connector 348. The shield 350 is preferably but not necessarilyintegrally formed with the motor housing 330. Most preferably, theshield 350 is integrally formed with the upper end plate 334 of themotor housing 330.

Counterbored Rotor for Housing Bearings

In a preferred embodiment, the motor assembly 310 further includes upperand lower bearings 352 and 354, respectively, for rotatably supportingthe rotor shaft 324. The bearings 352 and 354 are preferably ballbearings; however, according to certain aspects of the invention, eachbearing may be of any type.

Preferably, the bearings 352 and 354 are disposed at least substantiallyadjacent one another. That is, the bearings 352 and 354 are disposedside by side so as to support the rotor shaft 324 only along thebearing-supported portion 346. One of ordinary skill in the art willtherefore understand the aforementioned cantilevered portion 344 tocomprise the portion of the rotor shaft 324 extending away from (i.e.,below) the lower bearing 254.

Preferably, the cantilevered portion 344 presents a length that isgreater than about one fourth (25%) of the total length of the rotorshaft 324. More preferably, the cantilevered portion 344 presents alength that is greater than one third (33%) of the total length of therotor shaft 324. Most preferably, the cantilevered portion 344 presentsa length that is nearly or about one half (50%) the total length of therotor shaft 324.

As best shown in FIG. 9, the rotor core 326 is at least in partsupported on the cantilevered portion 344.

In a preferred embodiment, a pair of snap rings 356 and 358 are providedto additionally secure the bearings 352 and 354 relative to thebearing-supported portion 346 of the rotor shaft 324. Alternative oradditional securement means may be provided, however, or snap rings orsimilar devices may be omitted.

Preferably, the motor housing 330 includes a bearing support 360 thatsupports the bearings 352 and 354. More particularly, the bearingsupport 360 preferably comprises a sleeve 362 that is spaced from andcircumscribes the rotor shaft 324, with the bearings 352 and 354likewise circumscribing the rotor shaft 324 and being interposed betweenthe sleeve 362 and the rotor shaft 324.

The bearing sleeve 362 is preferably integrally formed with the motorhousing 330. Most preferably, the bearing sleeve 362 is integrallyformed with the upper end plate 334 of the motor housing 330, such thatthe end plate 334 may suitably be referred to as an endshield. However,non-integral formation or formation separate from the upper end plate(e.g., formation associated with another part of the motor housing) ispermissible according to some aspect of the present invention.

The bearing sleeve 362 is preferably at least substantially cylindricalin form and is complementary in shape to the bearings 352 and 354.Alternative shapes are permissible, however. For instance, the sleevemight alternatively include an inner surface defining a generallycylindrical form in contrast to an outer surface defining a generallyprismatic form.

The rotor core 326 preferably is counter-bored in such a manner as todefine an axially downwardly extending recess or bore 368. Moreparticularly, the rotor core 326 preferably presents opposite upper andlower axial ends 364 and 366. The bore 368 preferably comprises acounterbore extending axially inwardly from the upper axial end 364.

The bore 368 is preferably concentric with the rotor shaft 324, althoughoffset configurations are permissible according to some aspects of thepresent invention.

The bearing sleeve 362 preferably projects axially downwardly into thebore 368 so as to be at least in part received therein. Alternativelystated, the rotor core 326 extends axially upwardly about the bearingsleeve 362 so as to at least substantially circumscribe the bearingsleeve 362.

Preferably, the bore 368 is at least substantially cylindrical andcomplements the shape of the sleeve 362, although disparate shapes arepermissible. For instance, the bore might instead be generally cuboidalin form.

Preferably, the lower bearing 254 is at least in part received in thebore 368. It is permissible according to some aspects of the presentinvention, however, for neither of the bearings to be received in wholeor in part in the bore or for both of the bearings to be received inwhole or in part in the bore.

As will be apparent to one of ordinary skill in the art, theaforementioned arrangement of the bearings 352 and 354, the bearingsleeve 362, and the bore 368 enables a reduction in the axial space thatwould otherwise be required for the bearings 352,354 and the rotor core326.

Axially Disposed Controller

The motor housing 330 preferably presents opposite, axially spaced apartupper and lower ends 370 and 372 defined by the shield 350 and the motorhousing shell 336, respectively. The rotor shaft 324 preferably projectsfrom the upper end 370 toward the lower end 372 (i.e., from a positionadjacent the shield 350 toward the shell 336).

Preferably, the motor assembly 310 further includes a controller 374(shown schematically in FIGS. 7-11) that is positioned adjacent thelower end 372 of the motor housing 330. That is, the controller 374 ispreferably positioned axially adjacent the encoder end 340 of the rotorshaft 324 to thereby be disposed axially below the rotor shaft 324.

The controller 374 is preferably configured to at least in part controloperation of the motor 312. More particularly, the controller 374preferably includes a printed circuit board 376 and a plurality ofelectronic components 378 (e.g., resistors, capacitors, inductors,transistors, processors, switches, etc.) mounted on the printed circuitboard. However, it is permissible for the controller to be configured inany manner known in the art.

The motor assembly 310 further preferably includes a controller housing380. The controller housing 380 preferably defines a controller chamber382 that at least substantially receives the controller 374.

The controller housing 380 preferably includes a base 384 and a sidewall386 extending axially from the base 384. The sidewall 386 is preferablygenerally cylindrical, although other shapes are permissible.

In a preferred embodiment, the shell 336 and the sidewall 386 are atleast substantially aligned. More particularly, the shell 336 and thesidewall 386 preferably form at least substantially coaxial cylindershaving at least substantially equal outer diameters.

Similarly, the motor chamber 332 and the controller chamber 382preferably have at least substantially equal diameters.

The sidewall 386 preferably defines a generally radially extending,circumferential shoulder 388. The shell 336 preferably engages and restsupon the shoulder 388 to at least in part secure the controller housing380 and the shell 336 relative to each other.

Furthermore, a plurality of fasteners 390 are preferably provided tosecure the controller housing 380 to the upper end plate 334 of themotor housing 330.

In a broad sense, the axial space savings described above with regard tothe bearings 352 and 354, the bearing sleeve 362, and the bore 368enables the provision of the axially disposed controller 374 asdiscussed above.

Recess-Defining Encoder Wheel

In a preferred embodiment, the motor assembly 310 additionally includesan encoder assembly 392 configured to sense an operational parameter ofthe motor 312. Most preferably, for instance, the encoder assembly 392senses at least one and preferably both of the position and speed of therotor 316.

As will be discussed in greater detail below, the encoder assembly 392is preferably at least substantially received in the controller chamber382.

In a preferred embodiment, the encoder assembly 392 includes an encoderwheel 394 fixed relative to the rotor shaft 324 for rotational movementtherewith. The encoder assembly 392 further preferably includes a sensedelement 396 fixed relative to the encoder wheel 394 to rotate therewith.Yet further, the encoder assembly 392 preferably includes a sensor 398operable to sense the sensed element 396. More broadly, the sensor 398is preferably operable to sense the speed and direction of the sensedelement 396 and, in turn, of the rotor 316 itself.

The sensor 398 is preferably fixed relative to the sensed element 396such that the sensed element 396 rotates relative to the sensor 398.More particularly, the encoder wheel 394 and the sensed element 396 arepreferably mounted to the cantilevered portion 344 of the shaft 324 atthe encoder end 340 to rotate therewith, whereas the sensor 398 ispreferably fixed to the controller 374. Other fixation locations arepermissible according to some aspects of the present invention, however.

The sensed element 396 preferably comprises a reflective code disc 400secured to the encoder wheel 394 by means of a pressure-sensitiveadhesive, although other sensed element types and securement means arepermissible. Most preferably, the reflective code disc 400 is awindow-type decal including hundreds of sensor-readable lines 402. Forinstance, a preferred reflective code disc might include one thousandtwenty-four (1024) radially extending, arcuately spaced apart linesprinted, etched, or otherwise displayed thereon.

The sensor 398 preferably comprises an encoder chip 404 fixed to theprinted circuit board 376 of the controller 374, although other sensorconfigurations fall within the ambit of some aspects of the presentinvention.

In a preferred embodiment, the encoder wheel 394 preferably presents agenerally cylindrical hub 406, a generally radially extending upperplate 408 extending radially outwardly relative to the hub 406, and agenerally cylindrical sidewall 410 extending axially downwardly from theupper plate 408. The hub 406 and the upper plate 408 each preferablycircumscribe and are fixed to the cantilevered portion 344 of the shaft324 at the encoder end 340, such that the encoder wheel 394 rotates withthe shaft 324.

The encoder wheel 394 preferably presents an at least substantiallyU-shaped cross-section so as to define an axially upwardly extendingrecess 412 therein. More particularly, as best shown in FIG. 9, theupper plate 408 and the sidewall 410 cooperatively present the generallyU-shaped cross-section. The upper plate 408, the encoder end 340, andthe sidewall 410 cooperatively define the recess 412.

As will be apparent from the above description, it is thereforepreferable that the rotor bore 368 and the encoder wheel recess 412extend in opposite axial directions, with the rotor bore 368 extendingaxially downwardly toward the encoder end 340 of the rotor shaft 324 andthe encoder wheel recess 412 extending axially upwardly toward theconnection end 338 of the rotor shaft 324.

Preferably, the encoder wheel 394 is integrally formed in its entirety.It is permissible according to some aspects of the present invention,however, for one or more portions of the wheel to be discretecomponents.

Preferably, the sidewall 410 presents a generally circumferentiallowermost encoder wheel face 414. The sensed element 396 (i.e., thereflective code disc 400 in a preferred embodiment, as illustrated) ispreferably adhered to the lowermost encoder wheel face 414.

The sensor 398 (i.e., the encoder chip 404 in a preferred embodiment, asillustrated) is preferably secured to the printed circuit board 376 ofthe controller 374 so as to be disposed immediately axially below thesidewall 410 and, in turn, the sensed element 396.

In a preferred embodiment, at least a portion of the controller 374 isreceived in the recess 412. For instance, as best shown in FIG. 9, it ispreferred that at least one of the electronic components 378 projectsinto the recess 412. One of more others of the electronic components 378preferably project axially upwardly outside the sidewall 410.

The above-described axial overlapping of the encoder wheel 394 and thecontroller 374 enabled by the provision of the recess 412 and the fittherein, as well as outside the sidewall 410, of the electroniccomponents 378 of the controller 374 enables a reduction in the axialenvelope required for the motor assembly 310.

Thus, a reduced axial envelope for the motor assembly 310, despite theaxial disposition of both the controller 374 and the encoder assembly392 relative to the motor 312, is cooperatively provided at least by (1)the compact positioning of the bearings 352 and 354 adjacent oneanother, rather than at opposite ends of the rotor shaft 324; (2) thereceipt of at least a portion of the bearing sleeve 362 (and the lowerbearing 354) in the recess 412 in the rotor core 326; and (3) the axialoverlapping of the encoder wheel 394 and the controller 374.

Turntable Motor Assembly—Second Preferred Embodiment

FIGS. 13-37 illustrate a second preferred turntable motor assembly 510.It is initially noted that, with certain exceptions to be discussed indetail below, certain elements of the turntable motor assembly 510 ofthe second preferred embodiment are the same as or very similar to thosedescribed in detail above in relation to the locomotion motor assembly110 and/or the turntable motor assembly 310. Therefore, for the sake ofbrevity and clarity, redundant descriptions and numbering will begenerally avoided here. Unless otherwise specified, the detaileddescriptions of certain of the elements presented above with respect tothe locomotion motor assembly 110 should therefore be understood toapply at least generally to the turntable motor assembly 510, as well.

Among other things, the turntable motor assembly 510 preferably includesa motor 512. The motor 512 preferably includes a stator 514 and a rotor516 rotatable about an axis.

The stator 514 preferably includes a generally toroidal stator core 518and wiring 520. The wiring 520 forms a plurality of coils 522 woundabout the stator core 518. As will be discussed in greater detail below,the wiring 520 further preferably includes exit wires or lead wires 524extending from the coils 522.

The rotor 516 preferably includes a rotor shaft 526 that is rotatableabout an axis, a rotor core 528 fixed to the rotor shaft 526 to rotatetherewith, and a plurality of circumferentially spaced magnets 530 fixedto the rotor core 528 to rotate therewith.

The motor 512 is preferably an inner rotor motor, with the stator 514 atleast substantially circumscribing the rotor 516.

The motor 512 further preferably includes a motor housing 532 defining amotor chamber 534. The stator 514 and the rotor 516 are preferably leastsubstantially received in the motor chamber 534.

The motor housing 532 preferably includes a generally circumferentialmotor shell 536, an upper end plate 538 fixed relative to the shell 536,and a generally radially extending lower end plate 540 fixed relative tothe shell 536 and axially opposite the upper end plate 538. The upperend plate 538 is preferably but not necessarily integrally formed withthe shell 536.

A connector 542 configured for engagement with a device or structuresuch as a turntable (not shown) of an automated guided vehicle such asthe robot 10 of FIGS. 1 and 2 is preferably provided. The connector 542is preferably configured to rotate in response to rotation of the rotorshaft 526.

More particularly, a gear assembly 544 preferably transfers rotation ofthe rotor shaft 526 to the connector 542. More particularly, the gearassembly 544 preferably decreases rotational speed from the rotor shaft526 to the connector 542 while increasing torque. Preferably, as bestshown in FIGS. 22 and 23, the gear assembly 544 includes an input gear546 and an output gear 548, with the input gear 546 drivingly engagingthe output gear 548. The rotor shaft 526 preferably includes an upperend 550 comprising the input gear 546. The output gear 548 and theconnector 542 are both preferably secured to an output shaft 552 torotate therewith. Thus, rotation of the output gear 548 results inrotation of both the output shaft 552 and the connector 542.

Although a gear assembly 544 as illustrated is preferred, a direct driveconfiguration is permissible according to some aspects of the presentinvention.

The motor 512 preferably includes a gear box 554 defining a gear chamber556 that at least substantially receives the gear assembly 544. The gearbox 554 preferably includes the upper end plate 538 of the motor housing532 and a top cover 558 secured to the upper end plate 538.

The connector 542 is preferably disposed axially above the cover 558 soas to be positioned outside the gear chamber 556.

The motor 512 preferably includes a pair of upper and lower rotor shaftbearings 560 and 562 for rotatably supporting the rotor shaft 526. Theupper end plate 538 preferably defines an upper bearing sleeve 564 forsupporting the upper rotor shaft bearing 560, while the lower end plate540 defines a lower bearing sleeve 566 for supporting the lower rotorshaft bearing 562. Thus, in the illustrated embodiment, the end plates540 and 538 function as motor endshields.

Yet further, the motor 512 preferably includes a pair of upper and loweroutput shaft bearings 568 and 570 for rotatably supporting the outputshaft 552. The cover 558 preferably defines an upper bearing sleeve 572for supporting the upper output shaft bearing 568, while the upper endplate 538 defines a lower bearing sleeve 574 for supporting the loweroutput shaft bearing 570.

Preferably, the shell 536 at least substantially circumscribes thestator core 518. Most preferably, the shell 536 is secured to the statorcore 518 via an interference fit, such that the shell 536 at leastsubstantially restricts axial shifting of the stator core 518. Theinterference fit is most preferably achieved via a hot drop operation(i.e., a thermal fitting operation). It is permissible, however, forother fit types or means of securement to be used. Preferably, however,the shell 536 restricts relative axial shifting of the stator core 518and, in turn, the stator 514 in general, during normal operation of themotor 512.

In a preferred embodiment, the motor 512 further includes a controller576 and a controller box 578. The controller box 578 preferably definesa controller chamber 580 that at least substantially houses thecontroller 576. The controller 576 is preferably configured to at leastin part control operation of the motor 512 and includes a printedcircuit board 582 and a plurality of electronic components 584 mountedon the board 582.

The controller chamber 580 is preferably disposed radially outside themotor chamber 534, although other arrangements (e.g., axially adjacentdisposition) are permissible according to some aspects of the presentinvention.

Preferably, the motor chamber 534 and the controller chamber 580 areconnected via a portal 586, as shown in FIGS. 22, 24, 28, and others. Aswill be discussed in greater detail below, at least some of the leadwires 524 are preferably routed through (i.e., extend through) theportal 586 to interconnect the stator 514 and the controller 576.

The controller box 578 preferably includes a main body 588 and a sidecover 590. The main body 588 is preferably but not necessarilyintegrally formed with the shell 536 of the motor housing 532.

The side cover 590 preferably but not necessarily includes a pluralityof fins 592 for dispersing heat from the controller 576.

As will be discussed in greater detail below, the motor 512 furtherpreferably includes an encoder assembly 594 and an encoder housing 596.The encoder housing 596 preferably at least substantially defines anencoder flywheel chamber 598. The encoder assembly 594 is preferably atleast substantially received in the encoder flywheel chamber 598.

Preferably, the motor housing 532 at least in part defines the encoderhousing 596. More particularly, the encoder housing 596 preferablyincludes the lower end plate 540 of the motor housing 532 and a baseplate 600 fixed to the lower end plate 540.

It is preferred that the encoder flywheel chamber 598 be disposed atleast substantially directly axially below the motor chamber 534. Moreparticularly, the lower end plate 540 preferably presents axiallyopposed inner and outer faces 602 and 604, respectively. The inner face602 is preferably adjacent the motor chamber 534 (and opposite theencoder flywheel chamber 598), whereas the outer face 604 is axiallyopposite the motor chamber 534 so as to be adjacent the encoder flywheelchamber 598. The base plate 600 is thus preferably fixed to the lowerend plate 540 adjacent the outer face 604.

The motor housing 532, the gear box 554, the controller box 578, and theencoder housing 596 each preferably comprise a metal such as aluminum,although other metals or types of materials may be used according tosome aspects of the present invention.

Staked Rotor

As noted above and as shown in detail in FIGS. 16-17 c, the rotor 516preferably includes the rotor shaft 526, the rotor core 528, and themagnets 530.

In a preferred embodiment, the rotor core 528 is a laminated rotor corecomprising a plurality of stacked laminations 606. Each of thelaminations 606 is preferably at least substantially circumferentiallycontinuous, and the laminations 606 are preferably at leastsubstantially uniform in axial height. However, it is permissibleaccording to some aspects of the present invention for the core to bedevoid of laminations (e.g., to have a solid form or comprise only apair of thick stacked portions), be formed of a plurality ofinterconnected arcuately arranged segments, or to include substantiallyirregularly sized laminations.

The rotor core 528 preferably presents axially spaced apart top andbottom faces 608 and 610 so as to define a rotor core axial heighttherebetween. The rotor core 528 also presents a radially outer face 612that preferably takes a generally cylindrical form to present a radiallyoutermost core diameter, although other rotor core shapes arepermissible according to some aspects of the present invention.

The magnets 530 each preferably present a pair of generally arcuatelyspaced apart magnet sides 614 defining a magnet tangential widththerebetween, upper and lower generally axially spaced apart magnet ends616 defining a magnet axial height therebetween, and inner and outergenerally radially spaced apart magnet fronts and backs 618 defining amagnet radial thickness therebetween. That is, in a preferredembodiment, each magnet 530 is preferably generally cuboidal in form.

Preferably, the rotor core 528 defines a plurality of arcuately spacedapart magnet-receiving slots 620, each of which receives a correspondingone of the magnets 530 therein. Preferably, each magnet 530 is receivedin its entirety in the corresponding slot 620, although partialinsertion is permissible according to some aspects of the presentinvention.

Preferably, each of the slots 620 extends axially through the entiretyof the rotor core 528 so as to present an axial slot height that is atleast substantially equal to the axial core height. Furthermore, theaxial slot height is preferably at least substantially equal to themagnet axial height.

Each slot 620 preferably presents first and second generally arcuatelyspaced apart slot ends 622 defining a slot tangential widththerebetween. The slot tangential width is preferably greater than themagnet tangential width, such that each of the slots 620 includes a pairof arcuately spaced apart end openings 624 defined adjacent respectiveones of the magnet sides 614.

In a preferred embodiment, the rotor core 528 further preferablyincludes a pair of arcuately spaced apart ears 626 associated with eachof the slots 620 and extending radially outwardly thereinto. The ears626 of each pair are preferably configured to cooperatively at least inpart position the corresponding one of the magnets 530 in thecorresponding slot 620. As best shown in FIG. 17a , such positioning maybe by means of restriction only upon generally circumferential shiftingof the corresponding magnet 530 (e.g., if the ears 626 are spaced aparta greater distance than the magnet tangential width). However, it isalso permissible that one or more magnets be sized to directly abut thecorresponding ears without shifting having occurred, whether by precisemanufacture or as a result of variation within sizing tolerances.

In a preferred embodiment and as best shown in FIG. 17b , each of theears 626 presents an ear axial extent that is at least substantiallyequal to the core axial height and, in turn, the magnet axial height.That is, each ear 626 preferably extends continuously alongside theentirety of the corresponding magnet side 614. It is permissible,however, for the ears to extend along only part of the correspondingmagnet and/or to be axially discontinuous so as to comprise a pluralityof axially spaced apart ear segments.

Preferably, the rotor core 528 also includes a pair of arcuately spacedapart bridges 628 each associated with a corresponding one of the slots620. Each bridge 628 is preferably disposed radially opposite acorresponding one of the ears 626 and radially adjacent a correspondingones of the end openings 624.

Each of the bridges 628 is preferably partly deformed to form asecurement portion 630 that extends into the corresponding one of theend openings 624 and engages the respective magnet 530, most preferablyvia contact with a corresponding one of the magnet sides 614. Thesecurement portions 630 of each pair of bridges 628 thus cooperativelyat least in part secure the respective magnet in the slot.

More particularly, each of the bridges 628 is preferably generallydisposed radially outside the corresponding one of the end openings 624,with the securement portion 630 extending radially inwardly into thecorresponding one of the end openings 624, and with a pair of thesecurement portions 630 engaging each of the magnets 530 alongrespective ones of the magnet sides 614.

It is particularly noted that the securement portions 630 thuspreferably cooperatively secure the magnets 530 not only againstgenerally circumferential and generally radial shifting, as will bereadily apparent to one of ordinary skill in the art, but also againstaxial shifting by providing frictional engagement with the magnets 530along the corresponding magnet sides 614.

Although direct contact is preferred, the securement portions mightalternatively be spaced slightly from the magnets so as to secure themagnets only upon shifting of the magnets into contact with thesecurement portions (see the above discussion with regard to the ears).

Furthermore, is permissible according to some aspects of the presentinvention for more broadly different positioning and extension of thesecurement portions to occur. For instance, the securement portionsmight extend radially outwardly from a radially inward position (e.g, inan outer rotor motor). In such a case, it may be preferable (but notparticularly necessary) for the ears to also be alternatively disposedso as to extend radially inwardly from a radially outward position, thusmaintaining the preferred opposed arrangement between the bridges andthe ears. It is also within the ambit of the present invention for thesecurement portions to be formed portions of the core other than thebridges (e.g., the bridges may be eliminated altogether).

Although it is preferred that both bridges 628 of each pair include acorresponding securement portion 630, it is permissible according tosome aspects of the present invention for only one bridge per pair toinclude a securement portion.

In a preferred embodiment, each securement portion 630 comprises a pairof axially spaced apart securement portion segments 630 a,630 b, suchthat four (4) of the segments 630 a,630 b (i.e., one upper segment 630 aand one lower segment 630 b adjacent each magnet side 614) cooperativelysecure each magnet 530 in the corresponding slot 620. More segments maybe provided, however, or the securement portions may be continuous(i.e., non-segmented).

Preferably, each of the securement portion segments 630 a,630 b isdisposed axially between the top and bottom faces 608 and 610 of therotor core 528 and, in turn, between the upper and lower magnet ends616. It is permissible according to some aspects of the presentinvention, however, for alternative positioning of the segments to beprovided. For instance, the magnets might alternatively be shorter inaxial height than the core, with one or more of the segments extendingpast the corresponding magnet end.

The securement portion segments 630 a,630 b preferably cooperativelypresent a total securement portion axial extent that is less than thecore axial height and, in turn, the magnet axial height. As shown inFIG. 17c , for instance, each securement portion 630 preferably does notextend alongside the entirety of the corresponding magnet side 614.Preferably, the total securement portion axial extent is between aboutten percent (10%) and about fifty percent (50%) of the core axialheight/magnet axial height. Most preferably, as illustrated, the totalsecurement portion axial extent is about twenty percent (20%) of thecore axial height/magnet axial height.

Alternatively stated, the plurality of laminations 606 forming the rotorcore 528 preferably includes a subset of laminations 606 a cooperativelydefining each securement portion 630. The subset of laminations 606 apreferably comprises between about ten percent (10%) and about fiftypercent (50%) of the plurality of laminations 606. Most preferably, asbest shown in FIG. 17c , the subset of laminations 606 a preferablycomprises about twenty percent (20%) of the total plurality oflaminations 606.

More particularly, as illustrated, the rotor core 528 preferablycomprises a stack of forty (40) laminations 606, with each of thesecurement portion segments 630 a,630 b being formed from four (4)laminations 606 a to define a securement portion-forming subset of eight(8) laminations 606 a.

Preferably, the slots 620, including the end openings 624, are devoid ofovermolding, adhesives or glues, fillers, or other means of providingadditional magnet securement. That is, it is preferred that thesecurement portions 630 and the ears 626 cooperatively providesufficient means of securing the magnets 530 in the slots 620, such thatprovision of additional means is unnecessary. Omission of suchadditional means may be preferable in some cases to avoid detrimentalelectromagnetic effects. However, it is permissible according to someaspects of the present invention for one or more additional securementmeans or mechanisms to be implemented.

According to some aspects of the present invention, formation of therotor core 528 and, more generally, the rotor 516 may be by any meansknown in the art. However, it is preferred that the rotor 516 is formedin a process that broadly includes (1) stamping or punching theplurality of laminations 606 from a thin metal sheet (e.g., a steelsheet) in such a manner that the ears 626 and the magnet-receiving slots620 are defined; (2) assembling the laminations 606 into an axial stackto form the rotor core 528; (3) inserting the magnets 530 intocorresponding ones of the slots 620; and (4) deforming the rotor core528 along the end openings 624 of each slot 620 to define the securementportions 630. However, according to some aspects of the presentinvention, deformation of the core need not be at the end openings 624of each slot 620. For example, in some instances, the core may bedeformed centrally between the slot ends.

With regard to step (4) above, such deformation is preferably achievedby means of one or more specially-designed tools (e.g., presses orstamps) that apply a radially inwardly acting force against the radiallyouter face 612 of the rotor core 528 to controllably “dent” selectedones 606 a of the laminations 606 and form one or more of the securementportion segments 630 a,630 b. Tool design is preferably such that such“denting” occurs without shearing or other damage to the selectedlaminations 606 a.

Most preferably, more than one tool is used simultaneously. Forinstance, a pair of tools may be provided in order to form an entiresecurement portion 630 (i.e., two axially aligned securement portionsegments 630 a,630 b) in one motion, with the rotor core 528 thereafterbeing rotated (on a turntable, for instance) to enable formation of anarcuately adjacent securement portion 630.

Alternatively, a plurality of arcuately spaced apart pairs of axiallyspaced apart tools, each corresponding with one of the desiredsecurement portion segments 630 a or 630 b, might be provided, with thetools simultaneously applying radially inward forces to form all of thesecurement portion segments 630 a,630 b concurrently.

As will be apparent to one of ordinary skill in the art, suchdeformation of the selected laminations 606 a to form the securementportions 630 will preferably result in the definition of acircumferential stressed region or band 632 extending along the portionof the outer face 612 of the rotor core 528 defined by the selectedlaminations 606 a.

The stressed region 632 preferably includes plurality of arcuatelyspaced apart primary stressed regions 632 a interconnecting each pair ofsecurement portions 630 and thus being disposed radially outside of andadjacent the magnets 530. The stressed region 632 further preferableincludes a plurality of arcuately spaced apart secondary stressedregions 632 b formed between the securement portions 630 of adjacentpairs and thus alternately arranged with the primary stressed regions632 a.

As best shown in FIGS. 17a and 17b , the primary and secondary stressedregions 632 a and 632 b cooperatively present a radially outermoststressed region diameter that is smaller than the core diameter. Theprimary stressed regions 632 a are thus operable to apply a radiallyinward force on the magnets 530 that additionally secures the magnets530 against shifting relative to the rotor core 528, both due to directgenerally radial force application and due to frictional forces.

It is permissible according to some aspects of the present invention,however, for the stressed regions to not apply significant force on themagnets under normal circumstances. For instance, the magnets might besized or positioned so as to not abut the stressed regions (i.e., to bespaced therefrom) or to abut them only lightly.

Ring for Axially Retaining Stator

In a preferred embodiment and as best shown in FIGS. 22 and 23, acircumferentially and axially extending space 634 is defined between thestator core 518 and the motor housing 532. The space 634 preferably inpart accommodates the coils 522, the lead wires 524, and other motorcomponents as required.

In a preferred embodiment, the space 634 is defined between the lowerend plate 540 and the rotor core 528. More particularly, the lower endplate 540 preferably defines a generally radially extending surface 636,with the space 634 being defined between the surface 636 and the rotorcore 528. It is permissible for such a radially extending surface to bedefined by any part of the housing, however. For instance, the housingmight include one or more projections (e.g., shelves, fingers, etc.)individually or cooperatively presenting a radially extending surface.

Preferably, the motor 512 includes a circumferentially extending statorretention ring 638, shown in detail in FIGS. 18-21 and in position inFIGS. 22-30, disposed in the space 634. The ring 638 preferably extendsat least substantially continuously, although it is permissibleaccording to some aspects of the present invention for the ring toinstead be discontinuous or to extend only along an arc rather thanforming a closed (or continuous) loop.

The ring 638 is preferably integrally formed. Most preferably, the ring638 is a molded element. However, it is permissible according to someaspects of the present invention for the ring to comprise a plurality ofdiscrete components.

The ring 638 preferably is formed of an electrically insulative materialsuch as a synthetic resin, although alternative materials, includingthose not suitable for use as electrical insulators, may be used withoutdeparting from the ambit of some aspects of the present invention.

The ring 638 preferably serves a variety of advantageous functions,several of which will be described in detail below.

Axial Retention of Stator

As noted above, a space 634 is preferably defined between the lower endplate 540 and the stator core 518. The ring 638 preferably at leastsubstantially spans the space 634 and at least in part restrictsrelative axial shifting between the stator core 518 and the motorhousing 532 or, more particularly, the stator core 518 and the lower endplate 540.

More particularly, as noted previously, the stator core 518 ispreferably secured to the shell 536 via an interference fit. Undernormal motor operation, it is therefore preferred the shell 536 securesthe stator core 518 against relative axial shifting between the statorcore 518 and the motor housing 532. However, should the fit loosen sosignificantly as to result in slippage of the stator core 518 relativeto the shell 536 and the remainder of the motor housing 532 (e.g., dueto a shock load, extreme thermal fluctuations, repeated thermalfluctuations over a significant enough portion of time, or othergenerally abnormal circumstances), the ring 638 would prevent extremeaxial shifting of the stator core 518. More specifically, the ring 638would prevent the stator core 518 and, in turn the stator 514, fromshifting into contact with the lower end plate 540 as the stator core518 slipped downward (due to gravity, for instance).

It is particularly noted, however, that while a secondary retentionfunctionality (the shell providing primary retention functionality) asdescribed above is preferred, it is permissible according to someaspects of the present invention for the stator retention ring toinstead be the primary means by which axially downward shifting of thestator core is restricted or prevented.

As noted previously, the ring 638 preferably comprises an electricallyinsulative material such as a synthetic resin. The lower end plate 540is therefore at least substantially insulated from the stator core 518and the wiring 520 by the ring 638.

Preferably, the ring 638 includes a circumferential outer wall 640presenting axially spaced apart upper and lower faces 642 and 644,respectively. The outer wall 640 preferably presents radially spacedapart inner and outer faces 646 and 648, with the outer face 648preferably abutting or being disposed in close proximity to the shell536.

The ring 638 further preferably includes a plurality of arcuately spacedapart crush ribs 650 disposed on the lower face 644 and configured toprovide additional structural integrity to the ring 638 when subjectedto axial loading. The crush ribs 650 cooperatively present a lowermostface 652 of the ring 638. It is permissible according to some aspects ofthe present invention, however, for the crush ribs to be omitted. Insuch a configuration, the previously described lower face of the ringwould also be the lowermost face of the ring.

The ring 638 preferably presents an axial height between the upper face642 and the lowermost face 652. In a preferred embodiment, the ring 638is sized axially in such a manner as to accommodate variations in theheight of the stator core 518 as might occur due to allowablemanufacturing tolerances. That is, the height of the stator core 518and, in turn, the axial dimension of the space 634, might vary frommotor to motor during manufacturing without such variation being deemeda defect. It is therefore preferred that the axial height of the ring638 be such that the ring 638 will appropriately fit in the space 634both when the stator core 518 is at its largest allowable specifiedaxial height and at its smallest allowable specified axial height.

Thus, in one configuration, as illustrated, the ring 638 might onlypartially (but preferably at least substantially) span the space 634 andbe in contact with the stator core 518, such that an axial gap 654 (bestshown in FIGS. 22 and 23 and included in the space 634) is definedbetween the lower end plate 540 and the ring 638.

Alternatively, in a second configuration, the ring might only partially(but preferably at least substantially) span the space and be in contactwith the end plate, such that the axial gap is defined between thestator core and the ring.

In a third configuration, the ring might only partially (but preferablyat least substantially) span the space and be in contact with neitherthe end plate nor the stator core, such that the axial gap includesupper and lower portions defined between the stator core and the ringand the between the ring and the end plate, respectively.

As will be apparent to one of ordinary skill in the art, in the firstand third configurations described above, maintenance of the gap betweenthe end plate and the ring prior to any attempted shifting of the statorcore 518 requires some form of support of the stator ring 638. That is,in a motor orientated as illustrated—in which the connector 542 isprovided at an axially upward end of the motor 512 relative to a globalreference system—and absent some form of support, the stator ring wouldsimply drop down toward the end plate due to gravity (see the secondconfiguration, above).

As will be discussed in greater detail below, such support mightprovided by structural features the housing. Alternatively, frictionbetween the ring and the housing, or any other suitable support means,might in whole or in part provide support to the ring. Such supportmeans might be either (1) sufficient to restrict axially downwardshifting of the ring prior to any attempting shifting of the stator corebut insufficient to support the ring when subjected to loads associatedwith an axially downwardly slipping stator core (e.g., low levels offriction or deflectable latches with a sufficiently low resiliency); or(2) sufficient to restrict axially downward shifting of the ring priorto and during any attempting shifting of the stator core (e.g., a solidshelf or plurality of fingers).

Turning again to the above-described first through third configurationsand considering the former case, in which slippage of the ring may occurupon loading associated with slippage of the stator core, any slippageof the stator core would be limited to the distance spanned by the axialgap. That is, the stator core can only slip so far as to close the axialgap. In the latter case, of course, no shifting of the stator core willbe permissible.

It is also noted that support means might be provided that allow somedegree of shifting of the ring without enabling complete closure of theaxial gap. For instance, a wedge-like surface might abut the ring insuch a manner as to enable shifting until the wedge-like surface “locks”the ring into place.

In a preferred embodiment, the axial dimension of the gap 654 is lessthan about ten-hundredths (0.10) inches, such that the maximum downwardstator core 518 slippage relative to the housing, before direct contactis achieved between the stator core 518, the ring 638, and the lower endplate 540, is ten-hundredths (0.10) of an inch.

One of ordinary skill in the art will recognize, however, that anappropriate gap size will be dependent on factors including but notlimited to the overall motor size, the stator core size, the enveloperequired for components to be fit in the space, the allowablemanufacturing tolerances for the stator core (and, in particular, itslaminations), and so on.

Furthermore, in a fourth configuration that contrasts with theaforementioned gap-defining configurations, the ring might span theentirety of the space, so as to directly abut both the core and the endplate with its upper face and lowermost face, respectively. In such aconfiguration, no axially downward slippage of the stator core couldoccur, even if fixation relative to the shell should fail.

Lead Wire Routing

In addition to the above-described stator-retention functionality, thering 638 further preferably functions to route the lead wires 524 thatextend from the coils 522, through the portal 586, and to the controller576.

More particularly, with regard to wire routing, the ring 638 preferablyincludes a plurality of arcuately spaced apart fingers 656 extendinggenerally radially inwardly from the outer wall 640. Each finger 656 isalso spaced axially from both the upper and lower faces 642 and 644,respectively, of the outer wall 640, so as to be spaced axiallydownwardly from the stator core 518.

Preferably, the fingers 656 are disposed in sets of arcuately evenlyspaced apart pairs, although an even distribution or other regular orirregular distribution falls within the ambit of the present invention.

As best shown in FIGS. 24, 27, and 28, the fingers 656 preferablyrestrict axially downward shifting of at least some of the wiring 520.More particularly, the fingers 656 preferably restrict such shifting ofat least some of the lead wires 524 as they extend generallycircumferentially along the outer periphery of the stator core 518.

In addition to routing, the fingers 656 also preferably assist inelectrical insulation of the lower end plate 540 from the wiring 520,which might otherwise fall or sag axially downwardly into contact withthe lower end plate 540.

Lead Wire Protection

In addition to routing the lead wires 524, the ring 638 preferablyfunctions to at least in part protect the lead wires 524. Moreparticularly, as will be discussed in greater detail below, the ring 638preferably functions to protect the lead wires 524 as they extendthrough the portal 586 from the motor chamber 534 to the controllerchamber 580.

Preferably, the motor housing 532 comprises a metal such as aluminum. Asbest shown in FIGS. 25-26 a, the portal 586 is preferably cut orotherwise formed through the shell in such a manner that the shell 536presents a sharp edge 658 adjacent the motor chamber 534 and a roundededge 659 adjacent the controller chamber 580. The sharp edge 658preferably includes a plurality of sharp edge sides 658 a, 658 b, 658 c,and 658 d at least in part defining the portal 586. The edge sides 658a, 658 b, 658 c, and 658 d preferably form a generally rectangularshape, although other shapes and/or numbers of edges are permissiblewithout departing from the scope of some aspects of the presentinvention. It is also permissible that some or all of the edges and/oredge sides be smooth or rounded rather than sharp, or vice versa.

As also best shown in FIGS. 25-26 a, in a preferred embodiment, the ring638 defines a lip 660 including a plurality of lip sides 660 a, 660 b,and 660 c. The lip sides 660 a, 660 b, and 660 c preferably extend overat least part and most preferably at least substantially the entirety ofeach of the corresponding edge sides 658 a, 658 b, and 658 c, such thatthe lip 660 extends over a portion of the edge 658.

The lip 660 thus prevents direct engagement between the lead wires 524and the covered portions of the edge 658 (i.e., the edge sides 658 a,658 b, and 658 c). Furthermore, as shown most clearly in FIGS. 24 and28, the fingers 656 assist in avoiding contact between the lead wires524 and the edge side 658 d by restricting axially downward shifting ofthe wires 524 prior to their extension through the portal 586.

Furthermore, in a manner similar to that discussed above with respect tomore generically described support structures, the lip 660 may alsofunction to restrict axial shifting of the ring 638 relative to themotor housing 532 both prior to and contemporaneously with attemptedaxially downward shifting of the stator core 518 relative to the motorhousing 532. For instance, as best shown in FIGS. 25 and 26, the lipside 660 a of the lip 660 preferably extends along almost the entiretyof the edge side 658 a so as to nearly abut the edge side 658 d. Thisnear-abutment enables the edge 658 to restrict axially downward shiftingof the ring 638 relative to the motor housing 532 and, in turn, axiallydownward shifting of the stator core 518 relative to the motor housing532 after only a very small amount of slippage (whether of the statorring 638 alone or of the ring 638 and the stator core 518 both) hasoccurred.

Stator Core Insulation

As noted previously, the ring 638 preferably comprises an electricallyinsulative material. As will be discussed in greater detail below, thering 638 is preferably configured to provide secondary insulation of thestator core 518.

More particularly, the stator 514 preferably includes a plurality ofelectrically insulative end caps cap 662, best shown in FIGS. 22 and28-30, cooperatively forming an electrically insulative covering that atleast in part overlies the stator core 518.

Each end cap 662 preferably includes upper and lower end cap segments662 a,662 b. As best shown in FIG. 28, the end cap segments 662 a,662 binclude respective generally radially outwardly and circumferentiallyextending rim portions 664 a,664 b, with the rim portions 664 a,664 bcooperatively forming at least substantially continuous upper and lowercircular rims 666 a,666 b, respectively. The rims 666 a,666 b preferablydirectly abut the stator core 518 and thereby provide electricalinsulation thereto.

Preferably, the ring 638 includes a shelf 668 extending generallyradially inwardly from the outer wall 640. The preferred shelf 668 isdisposed axially above the fingers 656. The shelf 668 preferably extendsat least substantially continuously circumferentially, althoughdiscontinuous or truncated extension is permissible according to someaspects of the present invention.

As best shown in FIG. 30, the shelf 668 is preferably disposed axiallybelow the lower rim 666 b in such a manner that radial overlap occurstherebetween. Such overlap is preferably of a non-contacting variety(i.e., an axial space 670 is preferably defined between the shelf 668and the lower rim 666 b), although direct abutment is permissibleaccording to some aspects of the present invention.

Furthermore, it is preferred that the shelf 668 overlaps only a portionof the lower rim 666 b. Full overlap is permissible according to someaspects of the present invention, however.

As best shown in FIG. 30, the aforementioned preferred partial overlapbetween the lower rim 666 b and the shelf 668 preferably results in thedefinition of a labyrinth 672 therebetween. The labyrinth 672 and theshelf 668 itself thus cooperatively provide a barrier against axiallyupward shifting of the lead wires 524 into contact with the stator core518. (As noted previously, the fingers 656 preferably cooperativelyrestrict axially downward shifting of the lead wires 524.)

Although some degree of overlap is preferred, it is also noted, however,that a non-overlapping shelf and rim might nevertheless cooperativelydefine some form of labyrinth or tortuous path that would restrict thelead wires from shifting into contact with the stator core.

End Plate Fastener Insulation

The ring 638 additionally preferably provides an electrically insulativebarrier about a plurality of fasteners 674 that secure the lower endplate 540 relative to the stator core 518. More particularly, the ring638 preferably includes a plurality of bosses 676 each defining afastener-receiving opening 678. As shown in detail in FIG. 29, eachfastener-receiving opening 678 preferably receives a corresponding oneof the fasteners 674 and at least in part insulates the correspondingfastener 674 from the wiring 520.

The bosses 676 are preferably evenly arcuately spaced apart.Furthermore, each boss 676 is preferably disposed arcuately between thefingers 656 of each of the aforementioned pairs of fingers 656, althoughother positioning and spacing is permissible according to some aspectsof the present invention.

Encoder Flywheel

As noted previously, the rotor 516 preferably includes the rotor core528, the magnets 530, and the rotor shaft 526, with the rotor shaft 526rotatably supporting the rotor core 528 and the magnets 530.

Furthermore, the motor 512 preferably includes the encoder assembly 594and the encoder housing 596, with the encoder housing 596 at leastsubstantially defining the encoder flywheel chamber 598. The encoderhousing 596 preferably includes the base plate 600 and the lower endplate 540 of the motor housing 532. The encoder flywheel chamber 598preferably at least substantially receives the encoder assembly 594.

In a preferred embodiment, the encoder assembly 594 includes an encoderflywheel 680 fixed to the rotor shaft 526 to rotate therewith. Theencoder flywheel 680 preferably includes a wheel body 682 and a sensedelement 684 secured to the wheel body 682 to rotate therewith.

More particularly, the wheel body 682 preferably includes radiallyextending flywheel disc 686 and a center wall 688 extending generallyaxially from the flywheel disc 686. The center wall 688 and the flywheeldisc 686 each preferably at least substantially circumscribe and abutthe rotor shaft 526 to cooperatively form a hub 690 for the wheel body682.

Preferably, as best shown in FIGS. 16 and 36, the rotor shaft 526includes an axially lower end 692 comprising a connecting element 694that drivingly engages the hub 690.

In a preferred embodiment, the sensed element 684 comprises a reflectivecode disc 696 similar to the previously described reflective code disc400 of the turntable motor assembly 310. It is permissible, however, foran alternative type of sensed element to be provided. Preferably,however, the sensed element 684 comprises at least one of a positionindicator and a direction indicator.

The sensed element 684 is preferably secured to the flywheel disc 686,although fixation to another component of the wheel body 682 ispermissible according to some aspects of the present invention.

Furthermore, the sensed element 684 is preferably secured to theflywheel disc 686 by means of a pressure-sensitive adhesive(particularly if in the preferred reflective code disc form). However,alternative securement by any means known in the art (e.g., discretefasteners, latches, other types of adhesives, etc.) is permissibleaccording to some aspects of the present invention.

The encoder assembly 594 further preferably includes a sensor assembly698 that is stationary relative to the encoder flywheel 680 andconfigured to sense the sensed element 684. The sensor assembly 698 isthus configured to sense rotation of the wheel body 682 and, in turn, ofthe rotor 516 in general.

Although any one or more of a variety of sensor types may be suitableaccording to some aspects of the present invention, it is preferred thatsensor assembly 698 include an encoder chip 700.

As noted previously, the encoder housing 596 includes the lower endplate 540, which presents inner and outer faces 602 and 604 adjacent themotor chamber 534 and the encoder flywheel chamber 598, respectively. Asbest shown in FIG. 36, the sensor assembly 698 is preferably fixed tothe outer face 604 of the lower end plate 540.

More particularly, the sensor assembly 698 preferably includes a bracket702 and a plurality of electronic components 704 fixed to the bracket702. The bracket 702 is preferably fixed to the lower end plate 540 bymeans of fasteners 706. Other fixation locations are permissibleaccording to some aspects of the present invention, however.

The electronic components 704 preferably include the encoder chip 700.The bracket 702 may be a printed circuit board or any other suitablestructure for enabling both support and operation of the electroniccomponents 704.

The rotor 516 and the encoder flywheel 680 each present respective rotorand encoder flywheel moments of inertia based on the respective massesand geometries thereof. The rotor 516 and the encoder flywheel 680further cooperatively present a total moment of inertia based on theircombined masses and geometries.

Preferably, the encoder flywheel moment of inertia is at least fifteenpercent (15%) of the total moment of inertia and less than or equal toabout ninety-five percent (95%) of the total moment of inertia. Morepreferably, the encoder flywheel moment of inertia is in a range fromabout twenty percent (20%) to about ninety-two percent (92%) of thetotal moment of inertia. In the illustrated embodiment, the encoderflywheel moment of inertia is preferably about twenty-one andfive-tenths percent (21.5%) of the total moment of inertia.

As will be discussed in detail below, the breadth of the above preferredranges is at least in part dictated by the allowable variations inpreferred configurations of the gear assembly 544.

More particularly, upon rotation at a given angular velocity, the rotor516 and the encoder flywheel 680 cooperatively present a total angularmomentum that is a function of the square of the angular velocity and ofthe total moment of inertia. Such angular momentum preferably assiststhe motor 512 in operating smoothly despite potentially detrimentaleffects such as gearing backlash, unexpected loading, and so on.

High gear ratios provided by an associated gear assembly (e.g., a 10:1ratio) result in significant slowing of the rotation of the connectorrelative to the rotor shaft. That is, the rotor and the encoder flywheelare spinning very quickly relative to the connector and provide a verylarge angular velocity contribution to the overall angular momentum.Thus, a high gear ratio enables a suitably high total angular momentumto be achieved in association with a greater reliance on angularvelocity than on mass (or, more broadly speaking, moment of inertia).

In contrast, a gear assembly having a low gear ratio (e.g., a 2:1 ratio)results in relatively insignificant slowing of the rotation of theconnector relative to the rotor shaft. That is, the rotor and theencoder flywheel are spinning only somewhat quickly relative to theconnector and provide a only a small or moderate angular velocitycontribution to the overall angular momentum. Thus, a sufficiently hightotal angular momentum perhaps cannot be achieved through significantreliance on angular velocity rather than mass/moment of inertia. Rather,it may be necessary to increase the total moment of inertia (e.g., byincreasing the density, radius, and/or axial thickness of the encoderflywheel and/or the rotor core, etc.) to achieve the desired angularmomentum.

A direct drive system in which rotor shaft speeds and connector speedsare at least substantially equal—in effect, a gear assembly having aone-to-one (1:1) gear ratio—may necessitate an even greater reliance onthe total moment of inertia to achieve suitable levels of angularmomentum.

Thus, as will be apparent to one of ordinary skill in the art, the totalangular momentum may be adjusted to meet overall motor performance needsthrough any one or more of a variety of design changes, including butnot limited to mass and/or geometric changes to vary the total moment ofinertia and gear ratio changes to vary the influence of angularvelocity.

However, as will also be apparent to one of ordinary skill in the art,the most desirable of such changes will vary according to factorsincluding but not limited to manufacturing expense, electromagneticconsiderations, and motor envelope. For instance, increasing the axialand/or radial dimensions of the encoder flywheel might be moreeconomically feasible than reconfiguring the manufacturing process toproduce a larger-diameter laminated rotor core and, in turn, a largerstator core to accommodate the enlarged rotor core. Increasing encodersize or rotor core size might be more desirable for economic or otherreasons than increasing the gear ratio. However, limits in motorenvelope might dictate that it is necessary both to increase the encoderflywheel and/or rotor size and to increase the gear ratio. For instance,the axial and radial space required for a large enough encoder flywheelmight simply not be available, necessitating an increased gear ratio.

In view of the above considerations, in a preferred embodiment of thepresent invention, it is generally desirable to avoid rotor coreredesign and to minimize the gear ratio as much as possible. Thus, toincrease angular momentum, the encoder flywheel inertia preferably isincreased to the extent allowed by the motor envelop (e.g, via increasesin axial thickness and/or outer diameter) before any gear ratioincreases are implemented in the gear assembly.

Turning now to specific examples, in the preferred illustrated turntablemotor assembly 510, the gear assembly 544 presents a six-to-one (6:1)gear ratio, with the encoder flywheel 680 presenting twenty-one and fivetenths percent (21.5%) of the total moment of the inertia. In contrast,an otherwise identical turntable motor having a direct driveinterconnection between the rotor shaft and the connector preferablyincludes an encoder flywheel that provides a much higher ninety-twopercent (92%) of the total moment of inertia.

In an alternative motor type (e.g., a locomotion motor similar to thelocomotion motor 114) with a twenty-to-one (20:1) gear ratio, theencoder flywheel might preferably provide thirty-nine percent (39%) ofthe total moment of inertia. In contrast, in an otherwise identicalalternative motor having a ten-to-one (10:1) gear ratio, the encoderflywheel might preferably provide a much higher eighty-five percent(85%) of the total moment of inertia.

As will be apparent from the above discussion of angular momentum andmoments of inertia, specific geometries of certain components of theturntable motor assembly 510, as well as certain relative dimensions ofvarious components, are significant factors in motor design.

For instance, as best shown in FIG. 35, the flywheel disc 686 presents aflywheel disc outer diameter OD_fly and a flywheel disc axial thicknessT_fly. The flywheel disc axial thickness T_fly is preferably greaterthan about three percent (3%) of the flywheel disc outer diameterOD_fly. More preferably, the flywheel disc axial thickness T_fly isbetween about four percent (4%) and about twenty percent (20%) of theflywheel disc outer diameter OD_fly. Most preferably, the flywheel discaxial thickness T_fly is about six percent (6%) of the flywheel discouter diameter OD_fly.

Furthermore, as noted previously and as best characterized in FIG. 35,the rotor core 528 presents a radially outermost core diameter OD_coredefined by the radially outer face 612, as well as a core axial heightH_core defined between the top and bottom faces 608 and 610. The coreaxial height H_core is preferably between about fifteen percent (15%)and about thirty-five percent (35%) of the core outer diameter OD_core.Most preferably, the core axial height H_core is about twenty-fivepercent (25%) of the core outer diameter OD_core.

Yet further, the flywheel disc axial thickness T_fly is preferablybetween about fifteen percent (15%) and about thirty-five percent (35%)of the core axial height H_core. Most preferably, the flywheel discaxial thickness T_fly is about twenty-five percent (25%) of the coreaxial height H_core.

Although the above description presents features of preferredembodiments of the present invention, other preferred embodiments mayalso be created in keeping with the principles of the invention.Furthermore, as noted previously, these other preferred embodiments mayin some instances be realized through a combination of featurescompatible for use together despite having been presented independentlyas part of separate embodiments in the above description.

The preferred forms of the invention described above are to be used asillustration only, and should not be utilized in a limiting sense ininterpreting the scope of the present invention. Obvious modificationsto the exemplary embodiments, as hereinabove set forth, could be readilymade by those skilled in the art without departing from the spirit ofthe present invention.

The inventors hereby state their intent to rely on the Doctrine ofEquivalents to determine and assess the reasonably fair scope of thepresent invention as pertains to any apparatus not materially departingfrom but outside the literal scope of the invention as set forth in thefollowing claims.

What is claimed is:
 1. A method of forming a rotor for use in a motor,said method comprising the steps of: (a) forming a core to define aplurality of arcuately spaced apart magnet-receiving slots; (b)inserting a plurality of magnets into corresponding ones of the slots;and (c) deforming the core along each of the slots to define asecurement portion that extends along and projects radially into thecorresponding slot to engage the respective magnet and thereby securethe respective magnet in the slot.
 2. The method as claimed in claim 1,step (a) including the steps of punching a plurality of laminations andstacking the laminations.
 3. The method as claimed in claim 2, step (c)including the step of stamping a selected number of the laminations sothat the securement portion has a total axial extent that is less thanthe core axial height.